textproduct: Quad Cities

KEY MESSAGES

- A strong storm system will bring the threat for severe storms once again to our area this afternoon and evening. SPC continues to highlight nearly our entire area in an Enhanced Risk (level 3 of 5) for severe weather.

- Much cooler conditions are expected this weekend. Unseasonably cool temperatures in the 30s Saturday night and Sunday night will bring the potential for frost/freeze, especially in our north.

- Area rivers are on the rise from the recent rounds of heavy rain, and heavy rainfall later today may push them even higher. Refer to the hydro section below for more details.

SHORT TERM /THROUGH TONIGHT/

Issued at 306 AM CDT Fri Apr 17 2026

Our active period of severe weather this week concludes today as yet another strong storm system approaches the area this afternoon and evening. An upper-level longwave trough over the northwestern CONUS will continue to translate eastward today, along with a southern stream impulse that will lift over our region this afternoon from the southern Great Plains. A warm/humid air mass will build over the area today, characterized by high temperatures warming to the upper 70s/lower 80s and dew points in the mid/upper 60s, should provide ample destabilization, with the 17.00z HREF ensemble mean progging SBCAPE values around 2500 to 3500 J/kg this afternoon before thunderstorm initiation. To the west, behind the approaching trough, is a surface cold front that will also approach the area this afternoon and act as a secondary mechanism for thunderstorm initiation. Storms are progged to fire off along the pre-frontal trough first approximately along the Mississippi River, with storms initially more discrete in nature. Given steep mid-level lapse rates, ample low-level SRH, and STP values around 2 to 4, large hail and strong tornadoes will be the primary hazards with these initial storms. The second area of convective initiation, along the cold front slightly farther west, will also occur this afternoon, so we're talking about two distinct areas of storm initiation. Now, while the storms that are progged to develop along the cold front will initially be discrete, they should grow upscale quickly into a QLCS, becoming more of a damaging wind threat. This line of storms should sweep through the area quickly once they grow upscale. SPC continues to highlight nearly our entire CWA within an Enhanced Risk (level 3 of 5) for severe weather today. Prior to the storms, gusty southerly winds will also be in place, with gusts around 40 mph.

As mentioned, all hazards are possible with today's severe weather threat, with a few strong tornadoes and significantly strong damaging winds becoming the main threats. Even after the storms develop into the QLCS late this afternoon into the early evening, the tornado threat doesn't appear to go away entirely as 0-3 km layer shear magnitudes appear strong enough along and north of Interstate 80 (35+ knots) to support mesovortexgenesis if there are any northeastward surges/bowing segments to take advantage of the low-level shear.

One other hazard that can't be ruled out is flash flooding, thanks to Pwat values in the 1 to 1.5 inch range, along with wet antecedent conditions. If storms can train over the same area, particularly once the QLCS develops, then flash flooding is a possibility, and there remains a Slight Risk (level 2 of 4) for flash flooding, mainly for areas along and south of a Sigourney, IA to Dubuque, IA line.

Eventually, severe storms will wane or move off to the east late this evening as the cold front sweeps through the area. Dry conditions should return by sunrise Saturday, with low temperatures falling to the lower 30s along the I-380 corridor to near 40s over west-central Illinois.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 306 AM CDT Fri Apr 17 2026

Much colder air will continue to move into the area for the weekend as a northwest flow pattern develops aloft. An area of high pressure will build into the area Saturday night, which could set up our first bout of frost/freeze conditions during the growing season. There does appear to be a mid-level trough sweeping through the area Saturday night, which could result in some cloud cover that could keep our temperatures from falling too much, limiting our frost/freeze potential. Despite this, the NBM probabilities of freezing temperatures Saturday night are still around 50-80% along and north of Interstate 80. Another night of frost/freeze conditions are possible Sunday night as well, with similar exceedance probabilities for freezing temperatures.

A quieter weather pattern will persist into early next week as a broad upper ridge remains in place through the central US. A larger trough begins to take shape across the western US into the latter portion of the week. Therefore, some warming and a move toward some smaller precipitation chances (20-40%) start to return to the area by Thursday with a larger storm system potentially nearing the region for Friday.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1239 AM CDT Fri Apr 17 2026

VFR conditions will continue through the morning hours today before a strong storm system crosses the area this afternoon and evening, bringing widespread showers and strong/severe thunderstorms (80-100% chances for rainfall). MVFR to IFR visibility reductions from heavy rainfall, along with MVFR ceilings, are expected with these storms.

With the potential for some locally strong winds with thunderstorms, continued to mention the potential for wind gusts in excess of 40 knots. If a storm becomes severe, gusts closer to 50 knots are NOT out of the question.

HYDROLOGY

Issued at 312 AM CDT Fri Apr 17 2026

What has changed...

River flood warnings have been issued for the Rock River from Como down to the mouth.

River flood warnings have been issued for the lower Iowa River at Wapello and Oakville along with the Cedar River near Conesville.

River flood warnings are now in effect for the Mississippi River from Muscatine down through Burlington and for Gregory Landing.

A river flood watch has been issued for the Mississippi River at Dubuque.

Discussion...

Over the past five days, multiple rounds of heavy rain have impacted eastern Iowa, northern Illinois and southern Wisconsin. Rainfall amounts have run from 2 to 5 inches of rain; much of this rain has been north of Highway 30.

Another round of heavy rain is forecast this afternoon and evening with amounts running from a half inch to around 1.5 inches. With area soils running from moist to near saturation, this additional rainfall will quickly run off into area waterways resulting in new or increased river flooding along with the potential for flash flooding.

Much of this rain is forecast to fall across southeast Iowa, west central Illinois and into northern Illinois. River basins impacted would be the Rock, lower Iowa, Skunk, Des Moines and La Moine.

Rock River...

Based on overall river forecasts and another round of heavy rain expected today, confidence is high (>80%) that the entire length of the Rock River will reach flood stage by the weekend and remain above flood stage into much of next week.

Mississippi River...

Routed flow coming down from the upper Mississippi, Wisconsin, Rock, Iowa and other tributary rivers will cause general rises along the length of the Mississippi. Based on the current routed flow and another round of heavy rain, confidence is high (>80%) that the Mississippi will reach flood stage from Muscatine down through Keithsburg and at Gregory Landing. Gladstone and Burlington are already above flood stage and will see additional rises as the additional routed flow arrives over the weekend and into next week.

Iowa Tributary Rivers...

Rivers in eastern Iowa are running high from the rounds of heavy rain. Flood warnings continue for the lower Wapsipinicon River near DeWitt and the Iowa River above Coralville near Marengo. Based on routed flow, the lower Cedar River near Conesville will go above flood stage over the weekend.

The North Skunk River near Sigourney is forecast to go above flood stage tonight with general rises expected farther downstream and on the Skunk River.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.